Seed germination is the growth of an embryonic plant contained within the seed, which emerges as a seedling having roots and shoots. Seed germination is the first critical phase in plant growth and development, and establishment of strong and healthy seedlings typically results in a higher yield crop production.
Seeds of most plant species contain an embryo and some store of food reserves. In seed germination, the food reserves are hydrolyzed (digested) by enzymes to provide substrates for energy as well as blocks of macromolecules for the emergence of shoots from the soil. The majority of the food reserve in the seed is starch, which is digested into sugar mainly by the catalyst of α-amylase.
Gibberellins have been used to trigger starch hydrolysis through inducing α-amylase synthesis in the aleurone cells. It has been demonstrated that gibberellins produced in the scutellum diffuse to the aleurone cells where they cause higher levels of transcription of the gene coding α-amylase and stimulate the secretion of α-amylase.
However, gibberellins also stimulate the elongation of the shoots by stimulating cell division and elongation. Application of exogenous gibberellins typically result in slender seedlings having weak steams that fall over easily and are less resistant to stresses such as drought, cold, heat, salt, flooding, and pathogen attacks. Gibberellin molecules may also be difficult to incorporation into stable products because they are typically unstable and may easily decompose in water.